Thermodynamic equilibrium compositions, structures, and reaction energies of [Pt.sub.x][O.sub.y] (x = 1-3) clusters from first principles

A combination of density functional theory calculations and ab initio thermodynamics are used to examine the equilibrium characteristics of a Pt atom, Pt dimer and Pt trimer confined to an idealized surface and in chemical equilibrium with an oxidizing atmosphere. The models have provided a systematic framework for understanding the compositions and energies of redox reactions of discrete metal clusters of interest in supported and gas-phase nanocatalysis.